Written by, MDNA Member Bob Yeoman, CEO of Yeoman Machinery Corporation– Elkhart, Indiana
The concept of forming a uniform profile by passing a flat metal strip through a series of mated tool dies that are mounted on consecutive stands with each set performing an incremental part of the bend that gradually forms the material into the desired cross- section is called Roll Forming. It is thought that Roll Forming began as early as 600 BC and processes were theorized by Leonardo da Vinci. One can say that the evolution of the application and use to American manufacturing to mass produce simple shapes come of age in about 1900.
ROLL FORMING TODAY
Roll forming is the most economical production process for the continuous bending of metal channels, angles, and complex shapes with multiple bends. Engineering and machine design can also allow for the addition of holes, notches, slots, and embossments. Specific configurations are consistently formed into long strips at a specific rate (Feet per Minute) from a coil of steel or nonferrous material. Roll Forming Machines work at room temperature in a continuous cycle where material passes through a number of stations (forming stand) where fixed rollers both guide the material and make the necessary bends. As the material strip travels through each successive station (roll former stands), the rolls bend the material a little bit more than the previous station. This progressive bending method ensures that the cross-sectional configuration will be achieved while maintaining the tolerances required for the finished shape. The typical operating speeds of a Roll Forming machines are between 30 and 600 feet per minute (FPM) which makes them the ideal choice for manufacturing large quantities of parts with a constant profile of varying length. Depending upon the type of material being formed (shaped), the final product will normally feature an excellent finish detail and should require little, if any, finishing work. Machines today are equipped with AC variable speed drives which are both more energy efficient and smother cycling during the run-up.
Today machines feature computer-aided tooling designs and thereby function at their maximum potential. Modern Machines built that have incorporated computer controlled programming provides the roll former with an internal “brain” that will catch product imperfections thereby minimizing damage and waste. If a designed section needs multiple holes or needs to be cut to a specific length a programmable logic controller will tighten tolerance levels and maximize accuracy. The addition of features, such as laser or TIG welding capabilities, can remove an entire step in the manufacturing process.
Typical Shapes produced by Roll Forming are:
• U – C – J Style Channels
• Angles & Z Bars
• Hat & Box Channels
• Hybrid & Complex Shapes
• Steel Building Components
ROLL FORMING MACHINE LINE
A Roll Forming Machine Line can be separated into four major parts:
1. Entry Section: Material is loaded to be fed into the first station (forming stand) – either in a sheet form or a continuous coil.
2. Station Rollers: Actual Rolling Forming occurs at each station and not only shapes the metal but serves as the driving force of the machine.
3. Cut Off Press: The finished profile is cut to a predetermined length. Since Roll Forming machines operate at fast speeds and are a continuously working machine, a flying die cut-off press is normally used.
4. Exit Station: Finished parts exit the Roll Forming Machine and onto a conveyor or table to be manually stacked or packaged.
USED ROLL FORMING MACHINE BASICS
The purchase of a Used Roll Forming Machine or a complete Line follows the exact decision process as one would employ when sourcing a new machine. Dimensional variation of a part created by roll forming is based upon the type of material used, the roll forming equipment in use and the actual application. Tolerances can be influenced by varying metal thickness, material spring back during production, the quality and wear of the tooling, the experience level of the machine operator and actual overall machine condition.
Quality late model used roll formers are always in demand and difficult to find. When looking around for a used machine it is important to understand the differences between manufacturers and how that might impact your tooling design, installation (or modification) of existing tooling your company might already have in use.
When looking around for a used Roll Former your part shape, roll dimension (roll space), material type and desired run speed will dictate what you will need to locate. Some basic machine terms and identification points are illustrated in the diagram below. They are important when discussing your machine requirements.
Machine Identification Points & Specifications:
A. Roll Space
B. Arbor Diameter
C. Arbor Key Size
D. Machine ( Base ) Width
E. Machine Length
F. Distance – Floor to Base of Machine
G. Dimension: Base to Centre Line of Lower Arbor
H. Dimension: Centre Line of Last Pass to End of Base
I. Dimension: Centre Line of First Pass to End of Base
J. Dimension: Horizontal Centre Distance Between Stands
K. Dimension: Vertical Centre Distance – Minimum / Maximum Adjustment
L. Number of Roll Forming Stands
M. Dimension: Centre Line to Roll Space Edge
N. Material Flow
O. Dimension: Machine Base to Pass Line
P. Dimension: Roll Space Edge to Outboard Face of Stand
Q. Dimension: Roll Space Edge to Inboard Face of Stand
R. Dimension: Stand Width
In summary, a general rule to justify a Roll Former is that it takes about 75,000 pieces of a given part per year. Roll Forming produces a more consistent part than other forming methods. Since Roll Formers run from a coiled material, product lengths are limited only by the amount of material in the coil. Machine configurations can be designed around the material type and part section (profile) required. Operations can be performed on the material in line prior to (PRE) and after (POST) running through the Roll Former before finished parts are cut to length. Most importantly, when looking for pre-owned equipment – seek out a stocking machinery dealer to serve your interests – they will be your most trusted and economic asset in meeting your requirements. Should you have any questions about Roll Forming machines, please do not hesitate to contact Bob Yeoman.
About the Author:
Bob Yeoman is President of Yeoman Machinery Corporation and founded the company in 1980. As the largest stocking dealer in Indiana, they specialize in all types of Metal Fabrication, Presses & Coil Handling, Broaching & Chip Making, and Roll Forming Machinery as well as performing Appraisal & Liquidation services. Members in good standing of MDNA, AMEA, and ASA. Bob Yeoman currently serves on the Board of Directors for the Association of Machinery & Equipment Appraisers and Machinery Dealers National Association. He is a member of Rotary International and serves on the Board of Directors for the Elkhart County Humane Society and is President of USTA/Northern Indiana Area.
You can reach Bob here: Phone: 574.295.6161 | Mobile & Text: 574.536.3400 | E mail: firstname.lastname@example.org
For more information on equipment or to buy, sell or trade you can also contact any of MDNA’s machinery dealers, located around the world, by using the Find Members>Search tool on mdna.org Or you can Find MDNA Members by region here.